Cable Management – Lateral Movement vs. Hoist Rate
For years, I taught that during a catenary hoist—when a swimmer remains on the hook and the aircraft moves laterally—a hoist capable of paying out or retrieving cable at a maximum of 250 feet per minute equates to roughly 2.5 knots of lateral movement.
In simple terms: if the aircraft moves away from the swimmer faster than ~2.5 knots, the cable will go taut; if it moves toward the swimmer faster than ~2.5 knots, the cable will go slack.
That’s a useful rule of thumb—particularly for pilots—but it represents a worst-case geometry and an oversimplification that can fall short in dynamic conditions.
During a catenary hoist, the hoist rate is variable—the lateral response is not linear.
Whether taking cable in or paying it out, the cable angle determines how cable speed is translated into horizontal movement.
For the examples below, assume a maximum hoist rate of 250 ft/min.
At reduced hoist rates, lateral movement scales accordingly—but the geometric amplification remains.
• As the cable approaches horizontal, lateral movement approaches the hoist rate (~2.5 knots).
• As the cable approaches vertical, lateral movement is amplified—dramatically.
From a 50-foot hover, as the cable steepens, the same 250 ft/min hoist rate produces approximately:
• ~2.8 knots at 100 ft of horizontal separation.
• ~3.5 knots at 50 ft.
• >12 knots at 10 ft.
This model is still simplified. It assumes straight-line geometry with a right angle at the water, while real-world hoists involve a catenary curve, drag, and system elasticity.
But the operational truth holds:
Dynamic maritime hoisting environments often require a drag to recover the swimmer. As the swimmer and survivor enter the capture radius and get closer to plumb, the ability to drive lateral movement during a drag increases rapidly.
That matters.
It defines when a crew can safely commit to the pickup—a critical decision point in heavy seas and surf where timing, precision, and cable management must align.
The Real Takeaway
The hoist does not control horizontal movement—it controls cable length.
Geometry—and ultimately the crew—controls everything else.
Hoist inputs near vertical cable angles produce larger lateral effects.
Experienced hoist operators and hoist riders (e.g., flight mechanics and rescue swimmers) understand this intuitively, but the numbers help pilots and less experienced operators better appreciate how lateral movement can be generated during a drag in dynamic hoisting conditions.
This concept can be a critical nuance for effective crew coordination.
It becomes more useful when paired with other advanced hoisting discussions on heavy seas and surf. The following posts are good examples of where it applies:
Heavy Seas and Surf Rescue Techniques – General – SPIRAL UP
Heavy Seas and Surf – Swimmer/Survivor Recovery Techniques – SPIRAL UP